Multi-channel audio signals are commonly used in combination with a set of speakers arranged to create a sound field that surrounds a listener. This effect is commonly called “surround sound.” Typically, the set of speakers is arranged so that there is a front center speaker, a surround left speaker, a surround right speaker, a front left speaker, a front right speaker and a subwoofer speaker. Other speaker arrangements are possible. Example formats for multi-channel audio signals for surround sound include, but are not limited to, DOLBY DIGITAL and DTS DIGITAL SURROUND.
In the production or editing of audio signals, such as the soundtrack for a motion picture, it is common to provide some mechanism to permit an editor to define the position of the sound field as perceived by a listener. In addition, it is common to provide some mechanism to permit an editor to define the motion of the sound field, i.e., to change to position of the sound field over time, as perceived by the listener. Changing the position of the sound field over time, herein called the motion of the sound, is commonly referred to as surround sound panning.
The mechanism for permitting an editor to define the position, and the change in position over time, of the sound field typically includes an input device and an output device. The input device permits the editor to specify positions and motion of the sound, whereas the output device displays to the editor the defined positions and motion. Such mechanisms are commonly provided in a control surface of an audio processing system. Such audio processing systems include, but are not limited to, audio mixers, consoles and digital audio workstations.
In the editing of multi-channel audio compositions, it is common to automate the controls applied to the audio signals. Automation is performed by recording the state of the controls over time, then “playing back” this control information. During playback, an editor may touch a control device on the control surface to modify the recorded control information. This capability of editing the recorded automation is enhanced by the use of touch sensitive or motion sensitive control devices. When a control device is touched, the recorded control information from that device is overwritten by new control information from that control device.
For surround sound panning, current control surfaces include devices such as a motorized joystick, a nonmotorized joystick combined with arrays of light emitting devices (LEDs), or one or more faders or encoders, either motorized or nonmotorized with an array of LEDs. Such devices also are commonly touch-sensitive or motion-sensitive. Motorized devices are designed to move during playback of recorded automation.